Printed circuit boards (PCBs) are commonly assembled by soldering electronic components to conductive traces on the PCB. These components can range in complexity from individual passive elements, such as resistors, to integrated circuits, to other circuit boards having previously constructed subassemblies, such as power converter subassemblies. The layout of the electronic components is primarily dictated by electrical considerations and mechanical considerations, such as the size and shape of the elements. In addition, some elements can generate a substantial amount of heat that is not easily removed from the PCB. Thermal requirements thus also must be considered in order to maintain the PCB components within predefined temperature limits.
Power converters are used to transform power at one set of conditions to another, and are becoming more commonly used as a PCB mounted subassembly. For example, a PCB having low operating voltage components but high current demand may be provided power by the use of a board-mounted power converter module (PCM) that is provided power from a high voltage power source via relatively smaller gauge wires.
PCMs dissipate large amounts of electrical power for their size, and, as a result, cooling these subassemblies is an issue. Several different PCM configurations are currently being sold to accommodate different board layouts, cooling air availability, and temperature requirements. Two common PCM configurations are “baseplate” models and “open-frame” models. In the baseplate model, a metal plate covers one surface of the PCB and acts as a heat sink for removing the heat generated by the components mounted on the PCB. A cooling air flow removes the heat from the baseplate/heat sink. In the open frame model, the cooling air flows directly across the PCB. No additional baseplate/heat sink is used. These models are different enough to preclude an economical module that is universally adaptable for use in different mounting configurations. As such, it is common for PCM manufacturers to produce PCMs having the same electronics but with different physical structures to accommodate different mounting configurations. This allows PCM manufacturers to develop a range of products to meet different electrical requirements, and allows the PCM purchaser the ability to separately select PCMs having different power conditioning requirements and mounting requirements.
For PCM manufacturers that attempt to meet the demands of a large number of customers, the common usage of different mounting configurations is problematic. Specifically, manufacturers are required to stock a large number of nearly identical electrical components. The need to stock multiple, non-interchangeable models is inconvenient and can be expensive for the subassembly manufacturers, and can make it difficult to keep the necessary stock on hand.
What is needed is an improved method of manufacturing electronic subassemblies having different mounting fixtures. The method should allow the manufacturer to maintain stocks of preassembled and pretested electronic assemblies and the ability to ship products to customers as they are needed. The resulting method should be compatible with manufacturing techniques and give the end user the ability to select between different mounting options.